祁连山林区青海云杉群落种子植物区系分析   总被引：2，自引：0，他引：2  

刘建泉  戴君虎  刘兴明  杨全生  郝虎  张元山  丁国民  王学福 《地理科学》2009,29(2)

根据祁连山林区青海云杉群落16块样地256个样方的调查结果,对青海云杉群落的植物种类和区系成分的多样性进行了研究,结果表明:青海云杉群落共有维管束植物96种,隶属25科52属;科的分布区类型以世界分布科为主,大部分主产温带;属的分布类型以温带性质居多,共31属59种,占总属数的62.26%,表明了青海云杉群落植物区系的温带性质;随海拔高度的变化,群落中不同林型的种数、属数和科数多样性表现出不同的变化规律,科和属的多样性最大值出现在山杨-青海云杉混交林中,种的多样性最大值出现在圆柏-青海云杉混交林中.  相似文献   

Roof Shale Flora of Coal Seam 6 from the Asselian（Lower Permian）Taiyuan Formation of the Wuda Coalfield, Inner Mongolia and Its Ecostratigraphic Significance     

ZHOU Weiming  SHI Guijun  ZHOU Zhiyan  WANG Jun 《《地质学报》英文版》2017,91(1):22-38

Roof shale floras help understand the transition of vegetational landscapes from a peat–forming environment to a clastic one, but are seldom investigated in the Cathaysian province(typical present day China and East Asia). Here the roof shale flora of Coal Seam 6 from the lower Permian Taiyuan Formation of the Wuda Coalfield, Inner Mongolia, is systematically described and its ecostratigraphic and phytogeographic implications are discussed. The flora is composed of seven plant groups, including Lepidodendrales, Medullosales, Gigantopteridales, Peltaspermales, Noeggerathiales, Cordaitales and Cycadales. Many of these taxa are also documented in Euramerica, and the floral composition indicates a more intimate relationship between Cathaysia and Euramerica during the Cisuralian than previously thought. However, there are few genera and species in common with those of the underlying peat–forming flora. Moreover, the flora is hardly comparable with the commonly known flora of the Taiyuan Formation. Such assemblage differences are very likely due to changes of taphonomic and environmental phases, rather than evolutionary floral succession. For a full and more precise understanding of the floral composition, succession and the floristic discrepancy in different depositional environments, an ecostratigraphic investigation on the Late Palaeozoic of Cathaysia is advocated.  相似文献   

Temporospatial dynamics and public health significance of bacterial flora identified on a major leatherback turtle (Dermochelys coriacea) nesting beach in the Southern Caribbean          下载免费PDF全文

Ayanna Carla N. Phillips  Johanna Coutou  Stacy Rajh  Neville Stewart  Antonio Watson  Adam Jehu  Hamish Asmath  Francis Dziva  Chandrashekhar Unakal  Ridley Holder  Raymond Raoul Carthy 《Marine Ecology》2017,38(2)

Grande Riviere beach, on the island of Trinidad, supports the largest nesting population of leatherback turtles in the Caribbean region. Throughout the nesting season, nests are naturally disturbed by newly nesting females, resulting in egg breakage and loss of some nest viability. This environment is ideal for the growth and proliferation of microorganisms. The range of bacterial flora present in beach sand and egg shells was examined, with emphasis on bacteria that may pose a threat to public and animal health. The extent to which the bacterial load and genera on the beach changed throughout the season was also assessed. Twenty‐five genera were identified, with Pseudomonas spp. found to be the most predominant environmental bacteria. Four genera identified possess zoonotic potential, while five additional genera are known to be of public and animal health significance. Distinct shifts in the density and distribution of bacteria were observed along the beach from early to peak nesting season. Shifts were seen across heavily traversed zones, thus highlighting the potential exposure threats posed to beach visitors and animals alike. Further studies aimed at speciating this population of bacteria, as well as isolating potential fungal pathogens may mitigate this threat. Identification of bacterial agents that are specifically pathogenic to leatherback turtles, turtle eggs, hatchlings and those who may interact with these animals will serve to enhance and guide efforts to better conserve this species and protect the health of all who visit this ecologically significant site.  相似文献   

On age of Nazimovskaya and Khasan formations in the Paleogene succession of southwestern Primor’e     

B. I. Pavlyutkin  S. I. Nevolina  T. I. Petrenko  T. K. Kutub-Zade 《Stratigraphy and Geological Correlation》2006,14(4):444-457

Materials of previous studies and new original geological and paleobotanic data are used to substantiate synchronism (late Eocene) of the Khasan and Nazimovskaya formations, the key stratigraphic units of the Paleogene in Primor’e. Coal-bearing sediments of the units rest upon early-middle Eocene volcanics (Kraskino rhyolite tuffs, Zaisanovka basaltic andesites) being overlain by the lower Fatash Subformation of the lower Oligocene with flora of the Kraskino type. The Ust’-Davydovskaya Formation of the Rechnoi Peninsula (outskirts of Vladivostok) is the most probable analogue of the Khasan (=Nazimovskaya) Formation.  相似文献   

Diatom-based ionic concentration and salinity models from the south Bolivian Altiplano (15–23 ° S     

F. Sylvestre  S. Servant-Vildary  M. Roux 《Journal of Paleolimnology》2001,25(3):279-295

The relationship between surface sediment diatom assemblages and measured limnological variables in fifty eight lake samples from the south Bolivian Altiplano was examined by constructing a diatom-water chemistry dataset. Analysis of this dataset by canonical correspondence analysis revealed that salinity and ionic concentration accounted for a significant amount of the variation in the distribution of the diatom assemblages. Two methods weighted-averaging regression and calibration, and by-class mean percentage table were used to established a transfer function for future reconstruction of past lake water salinity and ionic concentration in the southern Bolivian Altiplano. Weighted-averaging regression and calibration with inverse deshrinking provided a better model for the water chemistry reconstructions in this region.  相似文献   

漂浮海藻与海藻区系的关系   总被引：1，自引：0，他引：1  

刘正一  庞云龙  郭伟  秦松 《海洋科学集刊》2016,51(51):323-327

区系是海藻生物地理研究的基本单位,是以一定时间、空间范围内的全部海藻为对象划分的生物地理单元,具有相对稳定的温度性质、物种组成和边界范围,且区系之间具有较明显的差异。然而,长期以来海藻的区系研究仅以定生的底栖海藻为研究对象,对于漂浮海藻则没有明确的定位。近年来世界各地漂浮海藻造成的藻华频发,在一些海域漂浮海藻已成为周期性存在,同时分子技术的发展为海藻生物地理学研究提供了有力的支撑,为追溯、比较漂浮海藻及其与定生海藻的关系提供了可靠的参考。漂浮海藻对于认识全球变化和人类活动对海藻分布、适应与进化的影响具有重要研究意义。本文结合漂浮海藻的特点和海藻生物地理学的基本研究方法探讨漂浮海藻与海藻区系的关系。  相似文献   

中国西北甘肃地区华夏和安加拉混生植物群形成机制研究     

孙克勤  刘俊 《现代地质》2010,24(5)

系统总结了我国西北甘肃地区晚二叠世华夏和安加拉混生植物群的研究现状和研究进展,讨论了华夏和安加拉混生植物群的形成机制。早二叠世,塔里木板块和华北板块向西北运移,与此同时,哈萨克斯坦板块和西伯利亚板块向东南漂移。中二叠世,华夏古陆沿天山、阴山和大兴安岭一线与西伯利亚古陆碰撞导致古海洋闭合和山脉隆升,板块的碰撞为华夏植物群和安加拉植物群两者之间提供了"混生"的条件。来自这两个植物群的少数混生分子出现在本区的中二叠世晚期。晚二叠世,由于塔里木板块和华北板块与哈萨克斯坦板块和西伯利亚板块碰撞与联合,从而使华夏古陆和安加拉古陆对接,形成了华夏和安加拉混生植物群。华夏和安加拉混生植物群的分布模式可以归于陆地生态系统的板块运动、气候分异、环境变化、植物迁移和植物自身演化的结果。  相似文献   

藻蓝蛋白对博来霉素肺纤维化小鼠肠道菌群的影响          下载免费PDF全文

臧帆  李文军  秦松  林剑 《海洋科学》2023,47(6):42-51

博来霉素(bleomycin,BLM)是目前用于治疗头颈癌等多种癌症的药物之一,但会产生一系列副作用,例如肺纤维化(pulmonary fibrosis,PF),这大大降低了患者的生活质量。藻蓝蛋白(phycocyanin,PC)作为一种色素蛋白对包括PF在内的多种疾病具有调节作用。研究发现,慢性肠道疾病通常伴有肺部疾病,患者的肠道菌群会发生紊乱。针对上述线索,研究了PC对BLM诱导的PF小鼠肠道菌群的影响。通过尾静脉将BLM注入小鼠体内,以构建肺纤维化模型。然后通过16S r RNA高通量基因测序技术,分析了PC对BLM引起的PF小鼠肠道菌群的影响。结果表明,PC降低了BLM诱导的PF程度并调节了小鼠的肠道菌群。通过尾静脉注射BLM后,小鼠肺部受到损伤,肠道菌群发生紊乱。口服藻蓝蛋白干预后,小鼠的肺组织切片显示其胶原蛋白沉积减少,肺泡间隔和炎性细胞浸润减少,小鼠PF程度减轻。此时,小鼠肠道菌群中Alistipes、Lachnospiraceae等有益菌的丰度增加,Rikenella等有害菌的丰度降低,肠道菌群趋于正常。推测PC可以通过增加肠道中有益细菌的数量并减少肠道中有害细菌的数量...  相似文献